New Physics at TeV Scale & Precision EW Studies

Transcription

1 New Physics at TeV Scale & Precision EW Studies Steve Godfrey Carleton University LCWS 2005, Stanford, March S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 1

2 Why New Physics at TeV? Believe standard model is low energy effective theory Expect some form of new physics to exist beyond the SM Don t know what it is Need experiments to to show the way S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 2

3 Electroweak Symmetry Breaking Higgs Top/QCD SUSY New Physics Cosmology S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 3

4 Models of New Physics Little Higgs Extra dimensions (ADD, RS, UED ) Higgsless Model Extended gauge sectors (S. Nandi) Extra U(1) factors: Left-Right symmetric model: Technicolour Topcolour Non-Commutative theories Many, many models What do these models have in common? How do we distinguish them? S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 4

5 I want to focus on predictions of the models; NOT the theoretical nitty gritty details To sort out the models we need to elucidate and complete the TeV particle spectrum Many types of new particles: Extra gauge bosons Vector resonances New fermions Extended Higgs sector Pseudo Goldstone bosons Leptoquarks (Dimopolous) So start with a rather superficial overview of some recent models S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 5

6 Little Higgs The little Higgs models are a new approach to stabilize the weak scale against radiative corrections 10 TeV Arkani-Hamed et al hep-ph/ New Strong Dynamics Global Symmetry 1 TeV 100 GeV Symmetries Broken Pseudo-Goldstone Scalars New Gauge Bosons related to SU(2): New Heavy Top cancels quadratic divergences Light Higgs SM vector bosons & fermions Parameters: f~vev s, s : GB mixing angles S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 6

7 Extra Dimensions In most scenarios our 3-dimensional space is a 3-brane embedded in a D-dimensional spacetime Basic signal is KK tower of states corresponding to a particle propagating in the higher dimensional Space-time The details depend on geometry of extra dimensions Many variations S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 7

8 ADD Type of Extra Dimensions (Arkani-Hamed Dimopoulos Dvali) Have a KK tower of graviton states in 4D which behaves like a continuous spectrum Graviton tower exchange effective operators: Leads to deviations in dependent on λ and s/m H Also predicts graviscalars and gravitensors propagating in extra dimensions Mixing of graviscalar with Higgs leads to significant invisible width of Higgs S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 8

9 Randall Sundrum Model dimensional branes separated by a 5 th dimension Predicts existence of the radion which corresponds to fluctuations in the size of the extra dimension Radion couplings are very similar to SM Higgs except for anomalous couplings to gluon and photon pairs Radion can mix with the Higgs boson Results in changes in the Higgs BR s from SM predictions Also expect large couplings for KK states of fermions Expect supression of Enhancement of S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 9

10 Randall-Sundrum Gravitons: The spectrum of the graviton KK states is discrete and unevenly spaced Expect production of TeV scale graviton resonances in 2-fermon channels Has 2 parameters; mass of the first KK state coupling strength of the graviton (controls the width) S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 10

11 Universal Extra Dimensions Appelquist, Cheng, Dobrescu, hep-ph/ Cheng, Matchev, Schmaltz, hep-ph/ All SM particles propagate in the bulk Mass spectrum KK towers for SM particles with spin quantum numbers identical to SM particles Spectrum resembles that of SUSY Have conservation of KK number at tree level leading to KK parity = (-1) n possible decay chains Ensures that lightest KK partners are always pair produced So lightest KK particle is stable S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 11

12 Higher Curvature TeV-scale Gravity Rizzo [hep-ph/0503 ] EH is at best an effective theory below M * Terms from UV completion (strings?) may be important as we approach M * Implications are: KK mass shifts New features in Black hole production S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 12

13 Summary of Model Predictions Models Predict: Extra Higgs (doublets & triplets) Radions, Graviscalars Gravitons KK excitations of γ, Z, W Extra gauge bosons What do these models have in common? Almost all of these models have new s-channel structure at ~TeV scale Either from extended gauge bosons or new resonances How do we distinguish the models? Need to map out the low energy particle content S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 13

14 Precision Electroweak Measurements How do we discover the new physics? How do we identify the new physics? Likely that discoveries at the LHC will get us started But will need the ILC to discriminate between models Possible Routes: Direct Discovery Indirect discovery assuming specific models Indirect tests of New Physics via L eff Tools: Di-fermion channel Anomalous gauge boson couplings Anomalous fermion couplings Higgs couplings S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 14

15 LHC Discovers S-channel S Resonance!! Eureka! What is it? Many possibilities for an s-channel resonances: graviton, KK excitations, Z S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 15

16 LHC can give some information: KK (RS): D=0, D=πR Z : Rizzo, hep-ph/ Graviton KK s (RS) Rizzo, hep-ph/ Davoudiasl, Hewett Rizzo, PRD63, S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 16

17 Forward Backward Asymmetries KK: Rizzo, hep-ph/ D=0, D=πR Dittmar, Nicollerat, Djouadi, hep-ph/ LHC/LC Report Based on dσ/dm LHC can resolve to some extent but requires significant luminosity S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 17

18 But this is a LC talk Start by assuming the LHC discovers single rather heavy resonance What is it? Tools are: Cross sections & Widths Angular Distributions Couplings (decays, polarization ) S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 18

19 On resonance production of (RS) Gravitons Use angular distributions to test against different spin hypothesis Spin 2 Measure BR s to test for Universal couplings jj WW ZZ tt ll hh S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 19

20 Z couplings Extraction of Z couplings assuming M Z is known from LHC 95% C.L. bounds L=1 ab -1 ΔL=0.2%, P - =0.8, P + =0.6, ΔP=0.5% S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 20

21 Measuring Little Higgs Parameters J. Conley, M.P. Le, J. Hewett M H not known from LHC s fixed S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 21

22 UED KK Z Z s s Signals S. Riemann KK-number conservation n=0 n=1 n=2 ee qq ee μμ KK 2 γ 2, Z 2 f 0 f 0 couplings couplings much smaller than SM couplings γ 0,Z 0 ; γ 2,Z 2 Excluded at 95% C.L. γ 2 < 2 s Z 2 < 2 s for ΛR=20 S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 22

23 Indirect Signatures for Gravitons Interference of exchange of virtual graviton KK states with SM amplitudes ADD: Leads to deviations in dependent on both λ and s/m H SM Hewett, hep-ph/ Hewett, hep-ph/ S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 23

24 Limits on Λ H Osland Pankov & Paver hep-ph/ Hewett, hep-ph/ Can use multipole moments to distinguish spin 2 from spin 1 S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 24

25 ID ADD Graviton Exchange ID ADD Graviton Exchange Pankov & Paver hep-ph/ Suitable observables can divide possible models into subclasses To identify graviton exchange Forward-Backward Centre-Edge asymmetries: S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 25

26 ILC Vertex Detector S. Hillert b-tagging an extremely powerful tool in ID ing models So b-purity vs efficiency is an important issue Π(b) M Pt > 2 GeV L/D > 0.3 (LCWS04) L/D > 0.16 (ECFA workshop) L/D > 0.16, ISR off L/D > 0.16 v inner vtx b Luminosity and beam parameter measurements was another important issue discussed R. Ingbir & E. Torrence S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 26

27 Higgs Properties in RS Model B. Lillie Higgs Branching Ratios Higgs production enhanced at LHC and γγ reduced at ILC Higgs decays are substantially modified S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 27

28 Invisible Higgs Width in ADD Invisible Higgs Width in ADD M. Battaglia, D. Dominici, J. Gunion, J. Wells Relevant parameters are: Mixing between Higgs and graviscalar: ξ Number of extra dimensions: δ M D scale Invisible width due to mixing vs direct decay ILC can measure invisible width directly and using HZ production S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 28

29 Little Higgs vs SM Higgs Partial widths are modified due to heavy particles running in the loop and by shifts to the SM W boson and t-quark S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 29

30 Measuring Little Higgs Parameters J. Conley, M.P. Le, J. Hewett Hallmark of Little Higgs models is coupling of heavy gauge bosons to Zh Expect deviations from SM in σ Zh ILC covers most of the interesting parameter space confirms in some regions of parameter space feature of LH S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 30

31 UED K.C. Kong [hep-ph/ ] The KK spectrum in UED resembles that of SUSY Discovery Reach at LHC in LHC SUSY or UED? S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 31

32 UED K.C. Kong [hep-ph/ ] But spins of SUSY particles different from KK particles Use: CLIC study And angular distributions to Distinguish between UED and SUSY Can also use threshold scans And energy distributions S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 32

33 Precision Measurements and Effective Lagrangians W. Kilian P. Osland, A. Pankov & N. Paver Contact Interactions: New interactions can be parametrized in terms of 4-fermion interactions if s << Λ 2 g μ μ L = ηij ( f i γ f i )( F i γ F i ) 2 Λ M Z i, j= L, R Λij Contact terms related to Z parameters η Λ LL 2 η Λ RR 2 η = Λ LR 2 η Λ RL 2 Obtain similar expressions for leptoquark exchange etc g M e L Z ' S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 33 g M F L Z ' g M e R Z ' g M f R Z '

34 Trilinear γww Couplings in γγ γγ W + W S ee = 500GeV qqqq x K.Mönig, J.Sekaric DESY-Zeuthen J Z =0 1σ 1σ GeV Δλγ = Δ λγ = γe cos θ LΔt 160/230 fb -1 S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 34 γγ LΔt 1000 fb -1 e+e- LΔt = 500 fb -1 ΔL 0.1% 0.1% (1%) - Δκ γ / / 5.9 (28) 3.6¹ Δλ γ / / 5.6 (5.7) 11.0¹ λ γ ΔL = 0.1% ΔL = 1% κ γ

35 Strong EWSB 4 L4 = 2 16π P.Krstonosic Can parametrize weak boson scattering as quartic couplings in effective Lagrangian: Eg. α tr ( ) ( μ ν V V tr V V ) μ ν e + e _ W + W _ Z α 5 WWZ 80% e-right, 60% e+left 800 GeV 1 TeV Major step towards a full and consistent set of limits done α 4 S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 35

36 Black Hole Production at the ILC ADD: Modification of Black Hole Properties Rizzo [hep-ph/0503 ] Threshold shapes will tell us: (α,β,γ)... S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 36

37 Conclusions The Linear Collider can make precision measurements It is needed to disentangle the underlying physics If s-channel resonance discovered at LHC need ILC for precision measurements of its properties If light Higgs discovered at LHC need ILC to determine the underlying theory For certain new physics has higher reach than LHC precision measurements at LC using input from the LHC Need to continue to work on LHC physics to strengthen the argument that the ILC is needed S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 37

38 March 22, 20?? The Director of the ILCL issues a press release: This result will send theorists back to their drawing boards * S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 38

39 Thanks to: M. Battaglia, A. Birkedal, J. Conley, S. Hillert, R. Ingbir, W. Kilian, K. Kong, P. Krstonosic, B. Lillie, Moenig, S. Nandi, P. Osland, A. Pankov, N. Paver, J. Reuter, S. Riemann, T. Rizzo, J. Sekaric, E. Torrence Grateful for all the assistance the speakers gave me! Linda Hopson S. Godfrey, Carleton University LCWS05: New Physics at TeV Scale and Electroweak Studies 39